2.4 i beleive which is what i have WOOT i love my car

 

lmao

 

haha yea i know

 

OK so what are the actual numbers then? and would it be the same on an auto tranny.

 

30% powerloss is BS! This guy has no clue what he is talking about. There is no way a FWD car looses that much power! That would mean a stock 171 HP 2.4L SS is only making 119.7 HP at the wheels!!!!

On a FWD car the engine usually attatches straight to the transmission which then sends power straight to the front axle. At most, there is like 12-14%, if that. Most AWD cars don't suffer 30% power loss at the wheels!

Motor Trend did an article titled "The Right Stuff" where they tested the Z06, Viper Coupe and Ford GT (December 2005). They took each car and dynoed them on a Mustang dyno. Their dyno guy said the normal HP loss for a RWD manual transmission car with independent suspension is 14-15% of crankshaft HP. A FWD car has to be less!

A front-engine, RWD car runs power from the flywheel to the transmission, through a big long driveshaft to the rear axle (the Corvettes transmission is mounted on the rear axle). This would produce more power loss than a FWD car! AWD would be the worse because of all the power loss through the drivetrain! So how is it that a FWD car looses 30%???? That is such BS!!!!

I don't really trust all these dyno figures that are posted on this site. Some are obviously overestimated figures. These machines are notoriously innacurate if they are not properly calibrated. Also, not all of them simulate actual road and aerodynamic loads to present more realistic results. The one used by Motor Trend did this (it was a state of the art 200-mph Mustang eddy-current dynamometer). On that street tuner challenge show on speed, the Cobalt SS Supercharged stock got 196 WHP (about 4.5 % HP loss). That sounds much more accurate than the 220HP plus that some SS/SC owners have seen on the dyno. Not saying that all of them are wrong, but don't always assume that they are an accurate measure of actual wheel horsepower!

 

Agreed... theres no way we lose that much horsepower and if some way we do lose that much id sell it cause it wouldnt be worth it... we lose 14% if that...

 

I would like to know aswell if that would be the same for the auto.

 

I'm not saying I believe he gets 30% loss either. I just did the math to show what he was supposedly losing based on his numbers.

 

wow thats one confusing dyno:S

 

Dyno proven values for this engine on Solstices and Cobalts have shown between 20%~24% depending on FWD or RWD configuration.

Solstices with 177HP base are consistently showing 135HP to the wheels which translates to a near 24% drive train loss. Adding CAI + cat-back is consistently showing a gain of 10HP to the wheels, for a new max value of 145HP to the wheels. As you've all seen from GTPprix's Solstice dyno graphs LINK we're seeing another consistent 10HP~15HP gain putting cars around 155HP~160HP to the wheels.

I've analyzed all of the Cobalt dyno graphs posted so far and all of them are pointing to nearly the same values. Base Cobalts with a stock 171HP are dynoing near 137HP stock (yes that's correct a 20% drivetrain loss, 15% is a rule of thumb for some cars but NOT always true). Adding a CAI + cat-back is seeing the same ~10HP gain to around 147HP as Solstices are seeing, and now with several ECU retunes with dyno values you're also seeing the same 10HP~15HP gain depending on setup to around 160HP as seen here and by Brandon97Z's car.

If the 20% drivetrain loss holds as power increases that means a car making 160HP to the wheels would therefore be making 192HP to the flywheel.

 

youll find out soon when i dyno march 25th

 

Humh. The 2.4L cars must have a real power robbing drivetrain to loose that much. That sucks! Maybe some of these dynos are with newer engines. Sometimes engines take a good 4000-5000 miles before they are making real good power. That may partially explain these low wheel HP numbers from a stock car.

 

The variation we're seeing between low (~1000 miles) and high (~5000 miles) mile 2.4L VVT engines is small enough to chalk up to dyno varience, like in the 5HP range. I plan on trying to do some research to see what type of loss the 2.2L is really experiencing as well in it's different forms to see if it's the engine or the drivetrain on Cobalts causing the power loss.

The issue with the Supercharged SS is an issue of GM possibly under rating the engine, and boosted engines running more efficiently so you end up with less loss from the rated to actual values.

 

on the FWD SRT-4 with heavy ass Modular set up on the crank they lose about 12%

 

Looking over 2.2L Cobalt based care dyno graphs it seems that engine is averaging between 115HP~120HP to the wheels. There's too many people talking about how pimp their mods are but not enough getting actual dyno values though to get a more acurate average then that range. So for the lowest, mid, highest range these would be the % loss for each one are below. Also being a lower powered engine it plays slight havoc on the numbers more by making the varience in % much larger (3.8% varience) with smaller changes in HP values. For example the difference between 135HP and 140HP on a Solstice is only a difference of 2.5% in power loss.

115 = 21%
117.5 = 19%
120 = 17.2%

So 20% drivetrain loss on the Cobalt platform seems very acceptable based on these numbers. Now is this an issue of these engines, GM's rating of the HP (supposedly the 2.4L VVT uses the new SAE standard), the drive train, etc etc? I'm not really sure but it seems fairly consistent.

 

The problem is it's very hard to compare forced induction values to those of naturally aspirated because FI are more efficient engines and usually show less loss between rated and actual values in dynos. That might also be an issue of underated values playing havoc on the numbers, kinda like the SS/SC and it's values not making exact sense at first look.

 

161hp, not bad!

 

Jerry were you able to check fuel milage and hows the drivability ?

 

my fuel mileage went from 21 to 24.5 huge diff. between 250-270 to 350 miles per tank. driveabilty is great.

 

I think those estimates are a little high as a stock 2.2 Ion dynos about 119.5 HP to the wheels, stock crank HP is 140. that equates to about 15%. Which sounds about right...the numbers you posted would seem alot more accurate for an automatic transmission but not a manual.

Also mi6 I'm not sure what you're saying about the 4.5% loss. 4.5% loss of what? theres definitely alot more than 4.5% drivetrain loss. I would guess that a Cobalts crank HP is about 230HP...but of course there is always those factory freaks and those low ballers out there. Each car varies...also location and weather that day will alter results as well.

 

I'm glad to hear your Happy with your tune from Lyndon . I hope to get a couple more cobalts here in nj to flash for him.keep me posted as you drive it some more .

 

Like you said, it's an issue of the factory underrating stock crank hp numbers on F/I cars. Why do they do this? Insurance, sleeper effect, who knows? It could also be that because there tends to be a wider range of power output between factory "duds" and factory "freaks" with F/I cars, they underrate them in order to keep even the factory "duds" at or above rated hp. That, of course, leaves the majority significantly underrated and making much more power than claimed. This phenomenon, whatever the reasoning, can be seen in many recent F/I cars including the Ford GT (Claim: 550hp ; Actual: ~550whp), the '03-04 Mustang Cobra (Claim: 390hp ; Actual: 370whp), the SRT-4 (Claim: 215-230hp ; Actual: 230whp), and the Cobalt SS/SC (Claim: 205 ; Actual: ~215whp), among others.

It, however, has nothing to do with the fact that F/I engines are more efficient. Realistically, it makes virtually no difference what engine is actually connected to the drivetrain, the loss is based on the drivetrain, not the engine. If anything, the added power of the F/I engine would make the loss greater. For example, say I take a stock Kia Rio, and dyno it N/A and the dyno it after I install a turbo. Assuming the thing doesn't explode into a fiery ball, the drivetrain is not going to become any more efficient at transferring crank horsepower to the wheels just because there happens to be a turbo attached now.

Maybe that's not what you meant, exactly, but that's how I took it